Method of and apparatus for drying combustible materials



Jan. 1, 1929. 1,697,268

H. EVESMITH METHOD OF AND API ARATUS FOR DRYING COMBUSTIBLE MATERIALS Filed Sept. 20, 1926 2 Sheets-Sheet 2 Patented 1, 1929.

HANSEN EVESMITH,.OF FARGO, NORTH DAKOTA.

' amen or AND APPARATUS ro'n name comnusrnira MArmuALs.

Application filed September 20.1926; seriai'm. 136,634.

This invention relates to a method of and apparatus for drying lignite or the like and is especially designed .fOI reducing the 1 moisture content of lignite to a point where available require the 'coal to 4" or less.

with the products of the lignite is best adapted for combustion.

One of the principal objects of the invention resides inthe provision of a method and apparatus of this character which may be carried out at a comparatively slight ex pense by-reason of the fact that the lignite need not be crushed but is taken as it comes from the mines and dried by direct contact combustion of the fire whose fuel supply is the finely divided or powdered portion ofthe lignite being dried Heretofore in the art all practical driers' crushing of the lignite The chief disadvantage.

of this method resides in the fact that it of an apparatus embodying a 'ing a grate and a combustion produces far too much fine or powdered coal for which there is at present only a limited market. The lump coal brings a good price for domestic use and would bring a much higher price if dried tosome extent. The present invention resides in the provision furiiace havspace above the grate and also having a perforated re- I volving' drum mounted in the combustion the products eludes the possib space of the furnace; from the mine is fed into the drum and is passed through the drum by virtue of the inclination of the' drum and by virtue of the interior of the its passage through the drum jected to the direct action of of combustion which 'pass Due to the revolving-motion drum; Durin the coal is su therethrough.

ofthe drum the coal is subjected to continual agitationfacilitating the passage of the products of combustion therethrough. The high moisture content of the 'coal, the moisture content being usuallyat 35%, preility of the coal being ignited by this drying action and in fact the present method and apparatus the moisture content-is usually not reduced below It has been found that li 1136 coal having a moisture content of" a out 15% burns better and gives more satisfactory re-i sults than where the moisture content "is reduced belowthis amount. In its broader aspects the invention is. not limited to the.

provlsionof the rotary drum but contem--- plates means overlying the grate and ex-.;

'ing the present The coal as taken 3 with bustion space 10 is defined certain novel features of the construction,

material in a constant state material to be dried while v arrangement and combination of parts 5 which will be hereinafter more fully described and particularly pointed out in the appended clalms, reference being had to the accompanying drawings forming this specification, andin which;

Figure 1 is a view partly in'longitudinal central vertical elevation showing an ppara'tus embodyinvention, a Figures 2 and 3 are fragmentary views in elevation showing different drum con-- structions,

Figl ire 4 is a view in transverse vertical section. on the line 4-4 of Figure 1, and

Figure 5 is a similar view on the line 5-5 of Figure 1. Referring to the drawings the numeral 1 designates generall a furnace in which a grate 2 is provide The furnace is preferably elongated and the ate bars extend transversely between the side walls 3 there- 75. apart of of. At suitable intervals along the side walls fire doors 4 are provided. An air blast may be provided below the forcing air through a main air 6 which connects with a perforated air discharge pipe 7. Above the grate 2 a comand through this "combustion space a revolving drum 11 extends. 7 Above the revolving drum a bafile 13 is arran ed, the baffle causing the rodnets of com ustion to circulate aroun and through the drum before they can pass to 'the flue or stack 14.

o5 grate bypp y p p In .theembodiment of the invention shown the revolvin of an elon ated ho ow cylinder which-has internal ri s 15 adjacent its ends, the ribs valve '11 is in the'form i may be used for turnin the drum and one A for the purpose of such means is shown illustrating .as comprising a ring gear be employed for C within the drum.

. fixed to the .drum and driven by a pinion 21' actuated from an electric motor 22. The portion of the drum 11 located within the combustion chamber 10 is provided with a multiplicity of openings, the openings being shown as slots 25 in Fig.

trates that the drum may perforations or openings of relatively small circular form, as indicated at 26. Shts may be employed in lieu of the circular openings or slots, as illustrated at 27 in Fig. 3. To produce the required feed of the material through the drum the drum may be inclined, as shown in Fig. 1, and the feed effected by this inclination may be supplemented by feeding ribs 30. While. the drum is preferably .inclined it may be disposed horizontal by increasing the size and number of the feeding ribs. The lignite coal I is fed in any suitable manner into the high end of the drum and it passes through the drum under the influence of the inclination of the drum and under the action of the spiral ribs 30. Of course, during the passage from the bed of the fire although this is not absolutelynecessary. The products of combustion passin through'the openings of the drum and traversethe coal therein to partially dry in that the moisture content of the coal is reduced from about 35% to about 15%. If desired-fans or other means may drum 10 to withdraw the moisture but this drum 11 the sidewalls of the furnacehave internal enlargements providing con-verging surfaces 35 and 36, the converging surfaces terminating at the plane or level of the coal- As shown in Fig. 4 the surface of the coal'will lay on an incline due to the rotation of the drum and, therefore, the'sur'faces 35 and '36 terminate at different vertical heights. Theseeonverging surfaces prevent the products of combustionifrom passmg around the drum and insure their passage through thecoal within the'drum. N

This greatlv contributes 1. Figure 2 illusbe provided with the provision of internal spiral of the coal through the drum it is sub jected to the direct action of the flames or. ofthe products of combustion which rise from circulating air through the is not absolutely necessary. For the pur-- .drum the finely divided portion thereof drops down through the openings onto the fire .so that the furnace is" automatically stoked fromthe drier sincethe fuel supply is replenished by the powdered coal whic drops through the openings of the drum 11.

the apparatus and method because the powdered or finely divided coal is the least val-.

'uable-element and it. is used to carry out 7 process. The expense of crushi is avoided but its moisture conthe drying ing the coal tent is reduced to the point to give the coal the most desirable properties and sizes for market purposesv I claim:

L'In a machine of the character described,.a furnace comprising a gratea .a combustion chamber overlying the gra a slightly inclined perforated revolving dr extending through-the combustion chamber, means'carried by said drum for feeding materialthrough the interior thereof whereby the material ispartially dried by direct cencombustion, the I tact with the products 0 perforations of the drum being arranged to permit a. certain amount of the material to fall onto the fuel supply thereof.

scribed, a furnace having a grate and also having a combustion chamber overl grate, 7

through the combustion chamber, said furnace having'converging. walls lying closely adjacent portions of thedrum locatfire on the grate to replenish the b5 2. In a machine of the character de to the efiiciency of ing the and a perforated revolving rum ex} tending 10.

ed at the level of the material. in the I when the 'latter is rotated. s

3. .In a machine of the #character described, a bustion chamber overlying thegrate, and an furnace having a grate and a comelongated revolving drum: extending through I the comliustion chamber and .having staggered openings therein, the inner walls '0 the combustion chamber converging from the grate to opposed portions of the revol drum andterminating at the-level assume by the material in the drum when-the latter is rotated;

h 4. A machine for"partially drying lignite; coal and'includin'g a furnace having a coma revolving drum extending bustion space, I through-the combustion space of the furnace means within the furnace acting to concentrate the products of combustion on that part and adapted to receive the coal to be dried, Kermit the roughthej drumand through the coal therein, and

hill

of the drum occupied by the coal when the drum is rotated. j

5. A drier comprising combination" with a grate,of a rotatable drum a'd-acent.

the grate, and means associated wit "the drum for continuously suppl 'ng fuel there-- from to the grate when the rum is rotated.

6. The method of drying which comprises passing the material to be dried throu h a zone of heat, and utilizing a portion 0 the aggregates oi? the material being treated for fuel while the same are passing through the heating zone.

7. The method of drying combustible material which comprises passing the material to be dried under constant agitation through a heating zone and continuously supplying fuel to the-heating means from the material being dried as it passes through the heating zone.

8. The method of drying coal which comprises passing the same through a heating zone over a bed of burning fuel, while constantly permitting the fine particles of the coal to fall upon the fire bed to replenish the fuel thereof.

9. The method of drying combustible materials which comprises passing the same through a heating zone over a bed of burn.- ing fuel while replenishing the fuel by the constant addition of fine particles of thematerial as the same is passing through the heating zone.

a NSEN EVESMITH. 

